Sound absorbing construction



`Iuly 19, 1938. K, SUDELL 2,124,086

SOUND ABSORBING CONSTRUCTION Filed Dec. 21, 1935 3 sheets-sheet 1 3 Sheets-Sheet 2 vc/mo K. SLIDELL `SQUND ABSORBING CONSTRUCTION Filed D60. 21, 1935 n, Y ...W

July 19, 1938'.

July 19, K, SLIDELL 2,124,086

SOUND ABSORBING CONSTRUCTION Filed Dec. 2l, 1935 3 Sheets-Sheet 5 me/Lio@ eme/tdel,

Patented July 19, 1938 UNITED STATES PATENT oi-FicE SOUND ABSORBING CONSTRUCTION Kemper Slidell, Madison, Wis., assignor to C. F.

Burgess Laboratories, Inc., Chicago, Ill., a corporation of Delaware Application December 21, 1935, Serial No. 55,657

10 Claims. (Cl. 'Z2-18) 'I'his invention relates to an improved sound- Fig. 3 is a bottom view of the. tile shown in absorbing construction and to a method for pro- Fig. 2; ducing this construction. Figs. 4, 5 and 6 are sectional views of modica- At the present time it is the practice to mount tions; 5 soft sound-absorbing material such as hair felt, Fig. 7 is a diagrammatic view of a screen 5 soft asbestos, mineral wool and the like back of adapted for use in the manufacture of tile in a membrane such as perforated metal and other accordance with the invention;

stiif sheets, such as are described and claimed in Fig. 8 is a bottom view'of a screen made in ac Norris Patent No. 1,726,500, issued August 27, cordance with Fig. 7 with uniformly distributed 10 1929, or back of cloth or similar material. This plugged areas; 10 is done in part to give the construction a dec- Figs. 9 and 10 are similar bottom views but oratable finish. Although sound-absorbing pads with modifications in the shape and arrangement or tiles of denser material are used without a of the plugged areas;

decoratable membrane in acoustical installations, Fig. 11 is a section of another modification of l5 nevertheless these are usually too dense to have tile in unfinished condition; l5 a high sound-absorbing capacity. Fig. l2 is a section of the same in finished In said Patent No. 1,726,500, Norris points out form; that it is necessary to have only a small propor- Fig- 13 iS a plan View 0f a Ceramic tile having tion of a metal membrane perforated .to secure a StenCiled Coating applied t0 the Surface; the full absorption Value of the sound-absorbing Fig 14 1S a Side elevation illeleOf and 20 material back of it. I have applied this principle Fg- 15 is ef Perspective View 0f a modified form in my improved Construction of perforated members for the formation of a When a brous product with a high scundtile thereon absorbing value is formed in the Wet Way on a To secure the desired results mentioned above screen, the Surface adjacent the Suction side of I form or mold the sound-absorbing pads or tiles 25 the screen is usually dense, due to an accumulaon a' suitame Screen or other perforated Surface tion of the material next to the screen. This m usmg sultable material Such for example as forms a substantially non-sound-absorbing skin a pulpiof asbestos ber and bmder' The perfo or non-permeable facing. It has been thought rated Surface no has snau indenpamqns or re' necessary to remove this skin to make available casses as Shown so that bhe tesuitmg me .formed 30 the high soundabsorbing interior portion. It on It has-correspondmg projections' havmg .the has been the practice also to bore deep holes into Crosisectlonal appearance. of Flg' 1' BY usmg the pad or tile to secure the same result but such Suctlon on the mold a' densled surface 5km may holes detract greatly from the appearance of the be formed The mam body of the sound absorb ing material li has a dense surface or facing i2 35 mstauatlon and Catch du?" Aslde lom, lts 19W upon which are the distributed projections i3 sound-absorbing value, this dense skin 1s desircontaining porous sound-absorbing cores. If the able since 1t forms an easily decoratable surface indentations of the Screen o are made of unper and addestlffness t? ehe me or pad forated stock, as shown in Fig. e, the pulp is not 40 FOUQWmg the prmelple ef the Norris construe* densified as much in projections i3'. After the 40 tion, it is onlynecessary to remove small areas me has dried, the projections, which may be en of this dense skin to secure full advantage of the mejy porous or may consist of a porous Coro with sound-absorbing properties of the interior. If a deosied Skin, as Shown, are ground off or oththe S Omed. 0n a at Screen beCOmeS IleC- erwise removed to leave the plane Surface of Fig eSSalY t0 bere hOleS through this Skin 0r Othel- 2 in which the substantially non-sound-absorb- 45 Wise remove it locally but this often detracts ing surface I2 has thesmall bosses of sound-ab from the appearanee Where a Substantially plane sorbing backing projecting through it, i. e. dissuriace iS desired. tributed small sound absorbing areas i4 are eX- Iri the drawings Fig. l is a sectional view illusposed. Said areas, which are free of the additrating the formation of a tile on a screen or tional material necessary to make the dense 50 other foraminous member; facing, allow the sound waves incident on the FiE- 1S a SeCiiOIlal View 0f a tile With the facing to penetrate into the sound-absorbing DIOJeeiDIOIlS removed el With percus sound-abbacking. 1f desirable, the exposed areas I4 of sorbing areas Otherwise formed in the exposed sound-absorbing material may be allowed to prosurface 0f the tile; ject beyond the surface, as shown in Fig. 5, or 55 they may be finished to form 'slight depressions i432, as shown in Fig. 6.

By incorporating coloring vmatter in the soundabsorbing material before forming the tile, decorative effects may be obtained to obviate the necessity for decorating the tile after installation.

Another method by which a similar result may be obtained is by the use of the suction screen of Fig. '7. The screen is plugged at the areas l5 whereA the pulp is to remain porous, the dense areas forming where the screen is open as at it. By this method the dense and porous areas are not as clearly defined as when made by the previous method, but Fig. 2 is fairly illustrative of the product which is formed, except that the porous areas are much larger.

' Fig. 8 is a bottom view of the screen just referred to with round plugged areas spaced equal distances apart in longitudinal and transverse rows. Fig. 9 is a similar view withV the plugged areas in the form of squares arranged in longiy mation in the mold.

tudinal and transverse rows. Fig. 10 is a similar view with round plugged areas arranged in diagonal rows. The plugged areas may, of course, be in the form of long lines or bands spaced apart and running longitudinally across the screen or transversely, or both, i. e. with the bands intersecting to leave the hard or sound impervious areas of the finished tile, separate and distinct from each other. Various arrangements of the plugged areas may be devised to form ornamental designs, as will be apparent.

Instead-of forming the above tile with a dense surface as described, it is also possible ,to form the dense surface layer by using other materials than the back-up materials. These may be lincorporated in the surface layer during its for# In another vmodification the tile is formed with projections but with a more or less porous surface. Pitch, ro'sin, as

phalt, plaster or other densifying material Il, as shown in Fig. 11, is then incorporated'in this surface either beforev or after it has been dried, if the wet process is used. Duco or other paints may be sprayed onto said surface to penetrate it for a limited distance. The projections are then removed, as described previously, to leave porous openings M5 in the dense surface, comprising extensions of the sound-absorbing interior, as shown in Fig. 12. If the pitch, rosin, asphalt, plaster or other densifying material is omitted and the surface treated with the Duco or other paints only, the resulting product would appear substantially the same in cross section as Fig'. 12, except that the dense areas would be thinner. In other words, Fig. 12 may be taken as representing both forms of the invention.

The same effect, of alternating areas of porous material and of ydense material, may be obtained by impregnating and/or densifying, usually in a predetermined pattern, a portion of the surface of a sound-absorbing pad which hasl neither projectionsnor a dense surface, to thereby leave small porous areas comparable to what is shown `in Fig. 2, in which the total or aggregate of the porous areas is small as compared to the total area of the tile, following the disclosure of said Norris patent. Any other suitable design may be employed, in which the porous areas appear as detached areas or in which the dense areas appear as detached areas with porous strips or other shaped areas separating the same. A stencil is used advantageously to form'decorative designs simultaneously, the densifying material betotal.

aiaepee of arcoating, only a small amount penetrating the absorber. In other words, the densifying material may be raised more or less above the surface of the tile in what may be called patches.

Not only can the above treatment be applied to fibrous sound-absorbing material, but it may be applied to porous sound-absorbing mineral and ceramic bodies. A construction is illustrated in Figs. 13 and 14 where a .stenciled pattern is shown applied to a ceramic tile i8. The stencil i9, selected as illustrative of what may be used, has the form of a lattice grid, i. e. it is largely open, so that less than half, preferably, of the tile surface is covered. ,Said stencil is laid upon the upper surface of the' sound-absorbing tile, assumed to be face up, and paint or the like is then sprayed upon said tile through the openpatches, aggregate about 67% of the total area in this instance. There is also left a continuous network of exposed tile surfaces 2l, permeable to air-borne sounds. Any suitable pattern may be used.

The tile so formed, when mounted With others on a ceiling, is of course in inverted position, with respect to that shown, i. e. the treated surface faces downwardly as in the case of the other sound-absorbing treatments shown herein. However, any of the various forms of tiles herein may be mounted vertically or at an angle and in cases where a stencil is made use of, it may in some cases be applied to the bottom surface of an existing installation.'

Fig. 15 shows a perspective view of a perforated plate 22 of metal or other suitable mateduce a fibrous tile in the manner previously de.

scribed, but with porous `lines or bands thereon in the form of recesses or grooves, which will cause the dense areas to stand out as elevated patches. If the form is used upside down, the dense areas will be recessed or sunken below the level ofothe remaining areas which are in thel form of ridges.

'I'he percentage of permeable to impermeable areas will vary widely in the several forms of the invention, depending on the pattern desired. For example, in Fig. 3 the permeable areas comprise less` than 10% of the total. In Fig. 8 the permeable areas constitute about 20% of the In Fig. 9 said areas comprise about 25% of the total and in Fig. 10 said areas comprise about 39% o-f the total. As previously pointed out, however, the permeable areas may comprise quite a small proportion of the total area, without substantial loss of eiiciency from an acoustical standpoint.

This application is a continuation in part oi' my copending application Serial No. 503,977, led December 22, 1930.

'I claim: Y

l. A sound-absorbing construction comprising a body of sound-absorbing material, addi= tional material incorporated in a face only of said sound-absorbing material to form a more dense layer integral therewith and having a substantially smaller sound-absorbing value, the surface of said dense layer having distributed therein small areas of the more porous sound-absorbing body material, continuouswith the main body thereof.

2. A1 sound-absorbing construction comprising a body of sound-absorbing material, at least one surface layer thereof having additional material incorporated therein to form a skin more dense than said body and integral therewith, and having a substantially smaller sound-absorbing value, said surface skin being discontinuous to expose distributed small areas of the more porous sound-absorbing body material, continuous with the main body thereof, the exposed surfaces of said sound-absorbing and densled areas being in substantially the same plane.

3. A sound-absorbing construction comprising a body of fibrous sound-absorbing material,

a surface layer only thereof having additional material incorporated therein to form a more dense skin integral with said sound-absorbing brous material, and having a substantially smaller sound-absorbing value, said surface skin having distributed therein small exposed areas of the brous sound-absorbing body material, continuous with the main body thereof.

4. A sound-absorbing construction comprising a body of-fibrous sound-absorbing material, a surface layer only thereof having additional material incorporated therein to form a more dense skin integral with,said sound-absorbing fibrous material, and having a substantially smaller sound-absorbing value, said surface skin being discontinuous to expose distributed small areas of the fibrous sound-absorbing body material, continuous with the main body thereof, the exposed surfaces of said sound-absorbing and densifled areas being in substantially the same plane.

5. A sound-absorbing construction comprising a substantially uniform body of sound-absorbing material, at least one surface layer thereof being more dense, whereby it has a substantially smaller sound-absorbing value, said dense layer being discontinuous to expose distributed small areas of the sound-absorbing body material, continuous with the main body thereof, the

exposed surfaces of said sound-absorbing and densied areas being in substantially the same plane.

6. A sound-absorbing construction comprising a body consisting substantially of fibrous, sound-absorbing material, at least one surface layer thereof being more compact and having a substantially smaller sound-absorbing value, said surface layer being discontinuous to` expose distributed small areas of the fibrous soundabsorbing body material, continuous with the main body thereof, the exposed surfaces of `said sound-absorbingI and compact areas being in substantially the same plane.

7. A sound-absorbing construction comprising a body composed throughout of sound-absorbing material,l at least one surface layer thereof being impregnated with a material which renders the facing formed thereby substantially less .sound-absorbing, said facing having distributed therein small areas of the sound-absorbing body material, continuous with the main body thereof.

8. A sound-absorbing construction comprising a body of sound-absorbing material, at least one side of which has additional material incorporated therein to form a more dense layer integral with said sound-absorbing material and having a substantially smaller sound-absorbing value, said dense layer being discontinuous and surrounding small portions of said sound-absorbing body material continuous with the main body thereof, the exposed surfaces of said sound-absorbing material being continuous with the outer surface of said dense layer.

9. A sound-absorbing construction comprising a body of fibrous sound-absorbing material, a surface layer only thereof having more of said fibrous material compacted therein to form a dense skin having a substantially smaller soundabsorbing value, said ldense skin having distributed therein small exposed areas of the fibrous sound-absorbing material, constituting a continuation of the main body thereof.

l0. A. self-supporting sound-absorbing panel of porous material characterized by good soun-dabsorbing properties and having] substantially the same density throughout the interior of the mass, the exposed surface of said panel having a preponderance of distributed, stiff, dense areas capable of being painted without materially diminishing the sound-absorbing properties of the mass of sound-absorbing material, the latter being exposed to the sound waves between said areas.

KENIPER SLIDELL. 

